If I got good marks in neet but not eligible through board 50% criteria then what should I do to get admissions in MBBS college?????

Even if you secure very good marks in NEET UG Entrance Examination, you will be disqualified in the counseling process if you secure less than 50 percent aggregate in Physics, Chemistry and Biology. And, hence, you wont get admission in any of the medical colleges.

However, it is very rare that a candidate who will secure very good marks in NEET, would secure less than 50 percent in 12th Examination.

Hence I shall suggest you to secure more than 50 percent. Best of Luck.